TY  - JOUR
A1  - Ozcelikay, Goksu
A1  - Kurbanoglu, Sevinc
A1  - Zhang, Xiaorong
A1  - Söz, Çağla Kosak
A1  - Wollenberger, Ulla
A1  - Ozkan, Sibel A.
A1  - Yarman, Aysu
A1  - Scheller, Frieder W.
T1  - Electrochemical MIP Sensor for Butyrylcholinesterase
JF  - Polymers
N2  - Molecularly imprinted polymers (MIPs) mimic the binding sites of antibodies by substituting the amino acid-scaffold of proteins by synthetic polymers. In this work, the first MIP for the recognition of the diagnostically relevant enzyme butyrylcholinesterase (BuChE) is presented. The MIP was prepared using electropolymerization of the functional monomer o-phenylenediamine and was deposited as a thin film on a glassy carbon electrode by oxidative potentiodynamic polymerization. Rebinding and removal of the template were detected by cyclic voltammetry using ferricyanide as a redox marker. Furthermore, the enzymatic activity of BuChE rebound to the MIP was measured via the anodic oxidation of thiocholine, the reaction product of butyrylthiocholine. The response was linear between 50 pM and 2 nM concentrations of BuChE with a detection limit of 14.7 pM. In addition to the high sensitivity for BuChE, the sensor responded towards pseudo-irreversible inhibitors in the lower mM range.
KW  - molecularly imprinted polymers
KW  - biomimetic sensors
KW  - butyrylcholinesterase
KW  - o-phenylenediamine
KW  - rivastigmine
Y1  - 2019
U6  - https://doi.org/10.3390/polym11121970
SN  - 2073-4360
VL  - 11
IS  - 12
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Yarman, Aysu
T1  - Electrosynthesized Molecularly Imprinted Polymer for Laccase Using the Inactivated Enzyme as the Target
JF  - Bulletin of the Korean chemical society
N2  - The first molecularly imprinted polymer (MIP) for the recognition of the copper-enzyme laccase was successfully prepared by electropolymerizing scopoletin in the presence of alkaline-inactivated enzyme. Laccase-MIP and the control polymer without laccase (nonimprinted polymer, NIP) were characterized by voltammetry using the redox marker ferricyanide. After electropolymerization, the signals for ferricyanide for both the MIP and the NIP were almost completely suppressed and increased after removal of the target from the polymer layer. Rebinding of both inactivated and active laccase decreased the ferricyanide peak currents to almost equal extent. The relative decrease of signal suppression approached saturation above 10 nM. Furthermore, the surface activity of rebound laccase toward the oxidation of catechol was investigated. The surface activity approached saturation above 10 nM, a value close to the value of the measurements with ferricyanide. Interaction of NIP with laccase brought about a six times smaller signal of catechol oxidation.
KW  - Molecularly imprinted polymers
KW  - Biomimetic sensors
KW  - Laccase
KW  - Electropolymerization
KW  - Scopoletin
Y1  - 2018
U6  - https://doi.org/10.1002/bkcs.11413
SN  - 1229-5949
VL  - 39
IS  - 4
SP  - 483
EP  - 488
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Yarman, Aysu
A1  - Scheller, Frieder W.
T1  - How reliable is the electrochemical readout of MIP sensors?
JF  - Sensors
N2  - Electrochemical methods offer the simple characterization of the synthesis of molecularly imprinted polymers (MIPs) and the readouts of target binding. The binding of electroinactive analytes can be detected indirectly by their modulating effect on the diffusional permeability of a redox marker through thin MIP films. However, this process generates an overall signal, which may include nonspecific interactions with the nonimprinted surface and adsorption at the electrode surface in addition to (specific) binding to the cavities. Redox-active low-molecular-weight targets and metalloproteins enable a more specific direct quantification of their binding to MIPs by measuring the faradaic current. The in situ characterization of enzymes, MIP-based mimics of redox enzymes or enzyme-labeled targets, is based on the indication of an electroactive product. This approach allows the determination of both the activity of the bio(mimetic) catalyst and of the substrate concentration.
KW  - molecularly imprinted polymers
KW  - electropolymerization
KW  - direct electron
KW  - transfer
KW  - catalysis
KW  - redox marker
KW  - gate effect
Y1  - 2020
U6  - https://doi.org/10.3390/s20092677
SN  - 1424-8220
VL  - 20
IS  - 9
PB  - MDPI
CY  - Basel
ER  - 
TY  - GEN
A1  - Yarman, Aysu
A1  - Jetzschmann, Katharina J.
A1  - Neumann, Bettina
A1  - Zhang, Xiaorong
A1  - Wollenberger, Ulla
A1  - Cordin, Aude
A1  - Haupt, Karsten
A1  - Scheller, Frieder W.
T1  - Enzymes as tools in MIP-sensors
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Molecularly imprinted polymers (MIPs) have the potential to complement antibodies in bioanalysis, are more stable under harsh conditions, and are potentially cheaper to produce. However, the affinity and especially the selectivity of MIPs are in general lower than those of their biological pendants. Enzymes are useful tools for the preparation of MIPs for both low and high-molecular weight targets: As a green alternative to the well-established methods of chemical polymerization, enzyme-initiated polymerization has been introduced and the removal of protein templates by proteases has been successfully applied. Furthermore, MIPs have been coupled with enzymes in order to enhance the analytical performance of biomimetic sensors: Enzymes have been used in MIP-sensors as tracers for the generation and amplification of the measuring signal. In addition, enzymatic pretreatment of an analyte can extend the analyte spectrum and eliminate interferences.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1098 
KW  - enzymatic MIP synthesis
KW  - template digestion
KW  - enzyme tracer
KW  - enzymatic analyte conversion
KW  - molecularly imprinted polymers
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-474642
SN  - 1866-8372
IS  - 1098
ER  - 
TY  - JOUR
A1  - Ozcelikay, Goksu
A1  - Kurbanoglu, Sevinc
A1  - Yarman, Aysu
A1  - Scheller, Frieder W.
A1  - Ozkan, Sibel A.
T1  - Au-Pt nanoparticles based molecularly imprinted nanosensor for electrochemical detection of the lipopeptide antibiotic drug Daptomycin
JF  - Sensors and actuators : B, Chemical
N2  - In this work, a novel electrochemical molecularly imprinted polymer (MIP) sensor for the detection of the lipopeptide antibiotic Daptomycin (DAP) is presented which integrates gold decorated platinum nanoparticles (Au-Pt NPs) into the nanocomposite film. The sensor was prepared by electropolymerization of o-phenylenediamine (o-PD) in the presence of DAP using cyclic voltammetry. Cyclic voltammetry and differential pulse voltammetry were applied to follow the changes in the MIP-layer related to rebinding and removal of the target DAP by using the redox marker [Fe(CN)(6)](3-/4-). Under optimized operational conditions, the MIP/Au-Pt NPs/ GCE nanosensor exhibits a linear response in the range of 1-20 pM towards DAP. The limit of detection and limit of quantification were determined to be 0.161pM +/- 0.012 and 0.489pM +/- 0.012, respectively. The sensitivity towards the antibiotics Vancomycin and Erythromycin and the amino acids glycine and tryptophan was below 7 percent as compared with DAP. Moreover, the nanosensor was also successfully used for the detection of DAP in deproteinated human serum samples.
KW  - molecularly imprinted polymer
KW  - Daptomycin
KW  - platinum nanoparticles
KW  - gold
KW  - nanoparticles
KW  - modified electrodes
Y1  - 2020
U6  - https://doi.org/10.1016/j.snb.2020.128285
SN  - 0925-4005
VL  - 320
PB  - Elsevier Science
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Yarman, Aysu
A1  - Scheller, Frieder W.
T1  - How reliable is the electrochemical readout of MIP-sensors?
T2  - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2  - Electrochemical methods offer the simple characterization of the synthesis of molecularly imprinted polymers (MIPs) and the readouts of target binding. The binding of electroinactive analytes can be detected indirectly by their modulating effect on the diffusional permeability of a redox marker through thin MIP films. However, this process generates an overall signal, which may include nonspecific interactions with the nonimprinted surface and adsorption at the electrode surface in addition to (specific) binding to the cavities. Redox-active low-molecular-weight targets and metalloproteins enable a more specific direct quantification of their binding to MIPs by measuring the faradaic current. The in situ characterization of enzymes, MIP-based mimics of redox enzymes or enzyme-labeled targets, is based on the indication of an electroactive product. This approach allows the determination of both the activity of the bio(mimetic) catalyst and of the substrate concentration.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 960 
KW  - molecularly imprinted polymers
KW  - electropolymerization
KW  - direct electron transfer
KW  - catalysis
KW  - redox marker
KW  - gate effect
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-471608
SN  - 1866-8372
IS  - 960
ER  - 
TY  - JOUR
A1  - Yarman, Aysu
A1  - Jetzschmann, Katharina J.
A1  - Neumann, Bettina
A1  - Zhang, Xiaorong
A1  - Wollenberger, Ulla
A1  - Cordin, Aude
A1  - Haupt, Karsten
A1  - Scheller, Frieder W.
T1  - Enzymes as Tools in MIP-Sensors
JF  - Chemosensors
N2  - Molecularly imprinted polymers (MIPs) have the potential to complement antibodies in bioanalysis, are more stable under harsh conditions, and are potentially cheaper to produce. However, the affinity and especially the selectivity of MIPs are in general lower than those of their biological pendants. Enzymes are useful tools for the preparation of MIPs for both low and high-molecular weight targets: As a green alternative to the well-established methods of chemical polymerization, enzyme-initiated polymerization has been introduced and the removal of protein templates by proteases has been successfully applied. Furthermore, MIPs have been coupled with enzymes in order to enhance the analytical performance of biomimetic sensors: Enzymes have been used in MIP-sensors as tracers for the generation and amplification of the measuring signal. In addition, enzymatic pretreatment of an analyte can extend the analyte spectrum and eliminate interferences.
KW  - enzymatic MIP synthesis
KW  - template digestion
KW  - enzyme tracer
KW  - enzymatic analyte conversion
KW  - molecularly imprinted polymers
Y1  - 2017
U6  - https://doi.org/10.3390/chemosensors5020011
SN  - 2227-9040
VL  - 5
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Zhang, Xiaorong
A1  - Yarman, Aysu
A1  - Erdossy, Julia
A1  - Katz, Sagie
A1  - Zebger, Ingo
A1  - Jetzschmann, Katharina J.
A1  - Altintas, Zeynep
A1  - Wollenberger, Ulla
A1  - Gyurcsanyi, Robert E.
A1  - Scheller, Frieder W.
T1  - Electrosynthesized MIPs for transferrin
BT  - Plastibodies or nano-filters?
JF  - Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics
N2  - Molecularly imprinted polymer (MP) nanofilrns for transferrin (Trf) have been synthesized on gold surfaces by electro-polymerizing the functional monomer scopoletin in the presence of the protein target or around pre-adsorbed Trf. As determined by atomic force microscopy (AFM) the film thickness was comparable with the molecular dimension of the target. The target (re)binding properties of the electro-synthesized MIP films was evaluated by cyclic voltammetry (CV) and square wave voltammetry (SWV) through the target-binding induced permeability changes of the MIP nanofilms to the ferricyanide redox marker, as well as by surface plasmon resonance (SPR) and surface enhanced infrared absorption spectroscopy (SEIRAS) of the immobilized protein molecules. For Trf a linear concentration dependence in the lower micromolar range and an imprinting factor of similar to 5 was obtained by SWV and SPR. Furthermore, non-target proteins including the iron-free apo-Trf were discriminated by pronounced size and shape specificity. Whilst it is generally assumed that the rebinding of the target or of cross-reacting proteins exclusively takes place at the polymer here we considered also the interaction of the protein molecules with the underlying gold transducers. We demonstrate by SWV that adsorption of proteins suppresses the signal of the redox marker even at the bare gold surface and by SEIRAS that the treatment of the MIP with proteinase K or NaOH only partially removes the target protein. Therefore, we conclude that when interpreting binding of proteins to directly MIP-covered gold electrodes the interactions between the protein and the gold surface should also be considered.
KW  - Molecularly imprinted polymer
KW  - Scopoletin
KW  - Transferrin
KW  - Protein adsorption
KW  - Redox marker
Y1  - 2018
U6  - https://doi.org/10.1016/j.bios.2018.01.011
SN  - 0956-5663
SN  - 1873-4235
VL  - 105
SP  - 29
EP  - 35
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Jetzschmann, Katharina J.
A1  - Yarman, Aysu
A1  - Rustam, L.
A1  - Kielb, P.
A1  - Urlacher, V. B.
A1  - Fischer, A.
A1  - Weidinger, I. M.
A1  - Wollenberger, Ulla
A1  - Scheller, Frieder W.
T1  - Molecular LEGO by domain-imprinting of cytochrome P450 BM3
JF  - Colloids and surfaces : an international journal devoted to fundamental and applied research on colloid and interfacial phenomena in relation to systems of biological origin ; B, Biointerfaces
N2  - Hypothesis: Electrosynthesis of the MIP nano-film after binding of the separated domains or holocytochrome BM3 via an engineered anchor should result in domain-specific cavities in the polymer layer. Experiments: Both the two domains and the holo P450 BM3 have been bound prior polymer deposition via a N-terminal engineered his6-anchor to the electrode surface. Each step of MIP preparation was characterized by cyclic voltammetry of the redox-marker ferricyanide. Rebinding after template removal was evaluated by quantifying the suppression of the diffusive permeability of the signal for ferricyanide and by the NADH-dependent reduction of cytochrome c by the reductase domain (BMR). Findings: The working hypothesis is verified by the discrimination of the two domains by the respective MIPs: The holoenzyme P450 BM3 was ca. 5.5 times more effectively recognized by the film imprinted with the oxidase domain (BMO) as compared to the BMR-MIP or the non-imprinted polymer (NIP). Obviously, a cavity is formed during the imprinting process around the hiss-tag-anchored BMR which cannot accommodate the broader BMO or the P450 BM3. The affinity of the MIP towards P450 BM3 is comparable with that to the monomer in solution. The hiss-tagged P450 BM3 binds (30 percent) stronger which shows the additive effect of the interaction with the MIP and the binding to the electrode.
KW  - Molecularly imprinted polymers
KW  - Protein imprinting
KW  - Electropolymerization
KW  - Cytochrome P450
Y1  - 2018
U6  - https://doi.org/10.1016/j.colsurfb.2018.01.047
SN  - 0927-7765
SN  - 1873-4367
VL  - 164
SP  - 240
EP  - 246
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Scheller, Frieder W.
A1  - Zhang, Xiaorong
A1  - Yarman, Aysu
A1  - Wollenberger, Ulla
A1  - Gyurcsányi, Róbert E.
T1  - Molecularly imprinted polymer-based electrochemical sensors for biopolymers
JF  - Current opinion in electrochemistry
N2  - Electrochemical synthesis and signal generation dominate among the almost 1200 articles published annually on protein-imprinted polymers. Such polymers can be easily prepared directly on the electrode surface, and the polymer thickness can be precisely adjusted to the size of the target to enable its free exchange. In this architecture, the molecularly imprinted polymer (MIP) layer represents only one ‘separation plate’; thus, the selectivity does not reach the values of ‘bulk’ measurements. The binding of target proteins can be detected straightforwardly by their modulating effect on the diffusional permeability of a redox marker through the thin MIP films. However, this generates an ‘overall apparent’ signal, which may include nonspecific interactions in the polymer layer and at the electrode surface. Certain targets, such as enzymes or redox active proteins, enables a more specific direct quantification of their binding to MIPs by in situ determination of the enzyme activity or direct electron transfer, respectively.
KW  - Electropolymerization
KW  - Direct electron transfer
KW  - Redox marker
KW  - Epitope imprinting
KW  - Biomarker
Y1  - 2018
U6  - https://doi.org/10.1016/j.coelec.2018.12.005
SN  - 2451-9103
VL  - 14
SP  - 53
EP  - 59
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Yarman, Aysu
A1  - Kurbanoglu, Sevinc
A1  - Jetzschmann, Katharina J.
A1  - Ozkan, Sibel A.
A1  - Wollenberger, Ulla
A1  - Scheller, Frieder W.
T1  - Electrochemical MIP-Sensors for Drugs
JF  - Current Medicinal Chemistry
N2  - In order to replace bio-macromolecules by stable synthetic materials in separation techniques and bioanalysis biomimetic receptors and catalysts have been developed: Functional monomers are polymerized together with the target analyte and after template removal cavities are formed in the "molecularly imprinted polymer" (MIP) which resemble the active sites of antibodies and enzymes. Starting almost 80 years ago, around 1,100 papers on MIPs were published in 2016. Electropolymerization allows to deposit MIPs directly on voltammetric electrodes or chips for quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). For the readout of MIPs for drugs amperometry, differential pulse voltammetry (DPV) and impedance spectroscopy (EIS) offer higher sensitivity as compared with QCM or SPR. Application of simple electrochemical devices allows both the reproducible preparation of MIP sensors, but also the sensitive signal generation. Electrochemical MIP-sensors for the whole arsenal of drugs, e.g. the most frequently used analgesics, antibiotics and anticancer drugs have been presented in literature and tested under laboratory conditions. These biomimetic sensors typically have measuring ranges covering the lower nano-up to millimolar concentration range and they are stable under extreme pH and in organic solvents like nonaqueous extracts.
KW  - Biomimetic sensors
KW  - molecularly imprinted polymers
KW  - drug sensors
KW  - drug imprinting
KW  - electropolymerization
KW  - electrochemical sensors
Y1  - 2018
U6  - https://doi.org/10.2174/0929867324666171005103712
SN  - 0929-8673
SN  - 1875-533X
VL  - 25
IS  - 33
SP  - 4007
EP  - 4019
PB  - Bentham Science Publishers LTD
CY  - Sharjah
ER  - 
TY  - JOUR
A1  - Yarman, Aysu
T1  - Development of a molecularly imprinted polymer-based electrochemical sensor for tyrosinase
JF  - Turkish journal of chemistry
N2  - For the first time a molecularly imprinted polymer (MIP)-based sensor for tyrosinase is described. This sensor is based on the electropolymerization of scopoletin or o-phenylenediamine in the presence of tyrosinase from mushrooms, which has a high homology to the human enzyme. The template was removed either by treatment with proteinase Kor by alkaline treatment. The measuring signal was generated either by measuring the formation of a product by the target enzyme or by evaluation of the permeability of the redox marker ferricyanide. The o-phenylenediamine-based MIP sensor has a linear measuring range up to 50 nM of tyrosinase with a limit of detection of 3.97 nM (R 2 = 0.994) and shows good discrimination towards other proteins, e.g., bovine serum albumin and cytochrome c.
KW  - Molecularly imprinted polymers
KW  - biomimetic sensors
KW  - tyrosinase
KW  - electropolymerization
KW  - scopoletin
KW  - ophenylenediamine
Y1  - 2017
U6  - https://doi.org/10.3906/kim-1708-68
SN  - 1300-0527
VL  - 42
IS  - 2
SP  - 346
EP  - 354
PB  - Türkiye Bilimsel ve Teknik Araştırma Kurumu
CY  - Ankara
ER  - 
TY  - JOUR
A1  - Kurbanoglu, Sevinc
A1  - Yarman, Aysu
T1  - Simultaneous determination of hydrochlorothiazide and irbesartan from pharmaceutical dosage forms with RP-HPLC
T1  - Farmasötik Dozaj Formlarında TF-YPSK ile Hidroklorotiyazid ve
İrbesartanın Eş Zamanlı Tayini
JF  - Turkish journal of pharmaceutical sciences
N2  - Objectives: In this work, a simple and rapid liquid chromatographic method for the simultaneous determination of irbesartan (IRBE) and hydrochlorothiazide (HCT) was developed and validated by reverse phase high performance liquid chromatography (RP-HPLC). <br /> Materials and Methods: Experimental conditions such as different buffer solutions, various pH values, temperature, composition of the mobile phase, and the effect of flow rate were optimized. <br /> Results: The developed RP-HPLC method for these antihypertensive agents was wholly validated and IRBE was detected in the linear range of 0.1-25 mu g mL(-1) and HCT was detected in the linear range of 0.25-25 mu g mL(-1). Moreover, the suggested chromatographic technique was successfully applied for the determination of the drugs in human serum and pharmaceutical dosage forms with limit of detection values of 0.008 mu g mL(-1) for IRBE and 0.012 mu g mL(-1) for HCT. <br /> Conclusion: The proposed rapid analysis method of these antihypertensive drugs can be easily used and applied by pharmaceutical companies for which the analysis time is important.
N2  - Amaç: Bu çalışmada, irbesartan (IRBE) ve hidroklorotiyazidin (HCT) eşzamanlı tayini için basit ve hızlı bir ters fazlı yüksek performanslı sıvı
kromatografisi (TF-YPSK) yöntemi geliştirilmiş ve validasyon çalışmaları yapılmıştır.
Gereç ve Yöntemler: Deneysel koşullar; farklı tampon çözeltileri, çeşitli pH değerleri, sıcaklık, mobil fazın bileşimi, akış hızının etkisi gibi
parametrelerin üzerinden optimize edildi.
Bulgular: Bu antihipertansif ajanlar için geliştirilen TF-YPSK yönteminin tüm validasyon parametrelerine ilişkin çalışmalar yapılmış, ve IRBE 0,1-25
μg mL-1 doğrusal aralığında ve HCT 0,25-25 μg mL-1 doğrusal aralığında tespit edilmiştir. Ayrıca önerilen TF-YPSK yöntemi ile IRBE için 0,008 μg
mL-1 ve HCT için 0,012 μg mL-1 tayin alt sınır değerleri bulunmuştur. Geliştirilen yöntem, insan serumunda ve farmasötik dozaj formlarında bulunan
IRBE ve HCT’nin belirlenmesi için başarıyla uygulanmıştır.
Sonuç: Bu antihipertansif ilaçların miktar tayininde önerilen YPSK analiz yönteminin, analiz süresinin önemli olduğu ilaç firmalarında rahatlıkla
kullanılabileceği ve uygulanabileceği düşünülmektedir.
KW  - HPLC
KW  - irbesartan
KW  - hydrochlorothiazide
KW  - pharmaceutical dosage forms
Y1  - 2020
U6  - https://doi.org/10.4274/tjps.galenos.2019.76094
SN  - 1304-530X
VL  - 17
IS  - 5
SP  - 523
EP  - 527
PB  - Turkish Pharmacists Association
CY  - Çankaya-Ankara
ER  - 
TY  - GEN
A1  - Ozcelikay, Goksu
A1  - Kurbanoglu, Sevinc
A1  - Zhang, Xiaorong
A1  - Söz, Çağla Kosak
A1  - Wollenberger, Ulla
A1  - Ozkan, Sibel A.
A1  - Yarman, Aysu
A1  - Scheller, Frieder W.
T1  - Electrochemical MIP Sensor for Butyrylcholinesterase
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Molecularly imprinted polymers (MIPs) mimic the binding sites of antibodies by substituting the amino acid-scaffold of proteins by synthetic polymers. In this work, the first MIP for the recognition of the diagnostically relevant enzyme butyrylcholinesterase (BuChE) is presented. The MIP was prepared using electropolymerization of the functional monomer o-phenylenediamine and was deposited as a thin film on a glassy carbon electrode by oxidative potentiodynamic polymerization. Rebinding and removal of the template were detected by cyclic voltammetry using ferricyanide as a redox marker. Furthermore, the enzymatic activity of BuChE rebound to the MIP was measured via the anodic oxidation of thiocholine, the reaction product of butyrylthiocholine. The response was linear between 50 pM and 2 nM concentrations of BuChE with a detection limit of 14.7 pM. In addition to the high sensitivity for BuChE, the sensor responded towards pseudo-irreversible inhibitors in the lower mM range.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1138 
KW  - molecularly imprinted polymers
KW  - biomimetic sensors
KW  - butyrylcholinesterase
KW  - o-phenylenediamine
KW  - rivastigmine
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-501854
SN  - 1866-8372
IS  - 1138
ER  - 
TY  - GEN
A1  - Yarman, Aysu
A1  - Scheller, Frieder W.
T1  - The first electrochemical MIP sensor for tamoxifen
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - We present an electrochemical MIP sensor for tamoxifen (TAM)-a nonsteroidal anti-estrogen-which is based on the electropolymerisation of an O-phenylenediamine. resorcinol mixture directly on the electrode surface in the presence of the template molecule. Up to now only. bulk. MIPs for TAM have been described in literature, which are applied for separation in chromatography columns. Electro-polymerisation of the monomers in the presence of TAM generated a film which completely suppressed the reduction of ferricyanide. Removal of the template gave a markedly increased ferricyanide signal, which was again suppressed after rebinding as expected for filling of the cavities by target binding. The decrease of the ferricyanide peak of the MIP electrode depended linearly on the TAM concentration between 1 and 100 nM. The TAM-imprinted electrode showed a 2.3 times higher recognition of the template molecule itself as compared to its metabolite 4-hydroxytamoxifen and no cross-reactivity with the anticancer drug doxorubucin was found. Measurements at + 1.1 V caused a fouling of the electrode surface, whilst pretreatment of TAM with peroxide in presence of HRP generated an oxidation product which was reducible at 0 mV, thus circumventing the polymer formation and electrochemical interferences.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1046 
KW  - molecularly imprinted polymers
KW  - anticancer drug
KW  - tamoxifen
KW  - electropolymerisation
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-476173
SN  - 1866-8372
IS  - 1046
ER  - 
TY  - JOUR
A1  - Scheller, Frieder W.
A1  - Yarman, Aysu
A1  - Bachmann, Till
A1  - Hirsch, Thomas
A1  - Kubick, Stefan
A1  - Renneberg, Reinhard
A1  - Schumacher, Soeren
A1  - Wollenberger, Ursula
A1  - Teller, Carsten
A1  - Bier, Frank Fabian
ED  - Gu, MB
ED  - Kim, HS
T1  - Future of biosensors: a personal view
JF  - Advances in biochemical engineering, biotechnology
JF  - Advances in Biochemical Engineering-Biotechnology
N2  - Biosensors representing the technological counterpart of living senses have found routine application in amperometric enzyme electrodes for decentralized blood glucose measurement, interaction analysis by surface plasmon resonance in drug development, and to some extent DNA chips for expression analysis and enzyme polymorphisms. These technologies have already reached a highly advanced level and need minor improvement at most. The dream of the "100-dollar' personal genome may come true in the next few years provided that the technological hurdles of nanopore technology or of polymerase-based single molecule sequencing can be overcome. Tailor-made recognition elements for biosensors including membrane-bound enzymes and receptors will be prepared by cell-free protein synthesis. As alternatives for biological recognition elements, molecularly imprinted polymers (MIPs) have been created. They have the potential to substitute antibodies in biosensors and biochips for the measurement of low-molecular-weight substances, proteins, viruses, and living cells. They are more stable than proteins and can be produced in large amounts by chemical synthesis. Integration of nanomaterials, especially of graphene, could lead to new miniaturized biosensors with high sensitivity and ultrafast response. In the future individual therapy will include genetic profiling of isoenzymes and polymorphic forms of drug-metabolizing enzymes especially of the cytochrome P450 family. For defining the pharmacokinetics including the clearance of a given genotype enzyme electrodes will be a useful tool. For decentralized online patient control or the integration into everyday "consumables' such as drinking water, foods, hygienic articles, clothing, or for control of air conditioners in buildings and cars and swimming pools, a new generation of "autonomous' biosensors will emerge.
KW  - Biosensors
KW  - Molecularly imprinted polymers
KW  - Personalized medicine
Y1  - 2014
SN  - 978-3-642-54143-8; 978-3-642-54142-1
U6  - https://doi.org/10.1007/10_2013_251
SN  - 0724-6145
VL  - 140
SP  - 1
EP  - 28
PB  - Springer
CY  - Berlin
ER  - 
TY  - THES
A1  - Yarman, Aysu
T1  - Biomimetic sensors for substrates of peroxidases and cytochrome P450s
Y1  - 2012
CY  - Potsdam
ER  - 
TY  - JOUR
A1  - Yarman, Aysu
A1  - Scheller, Frieder W.
T1  - Coupling biocatalysis with molecular imprinting in a biomimetic sensor
JF  - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition
KW  - biomimetic sensors
KW  - electropolymers
KW  - enzymes
KW  - hierarchical structures
KW  - molecularly imprinted polymers
Y1  - 2013
U6  - https://doi.org/10.1002/anie.201305368
SN  - 1433-7851
SN  - 1521-3773
VL  - 52
IS  - 44
SP  - 11521
EP  - 11525
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Yarman, Aysu
A1  - Wollenberger, Ursula
A1  - Scheller, Frieder W.
T1  - Sensors based on cytochrome P450 and CYP mimicking systems
JF  - ELECTROCHIMICA ACTA
N2  - Cytochrome P450 enzymes (CYPs) act on more than 90 percent of all drugs currently on the market. The catalytic cycle requires electron supply to the heme iron in the presence of oxygen. Electrochemistry allows to characterise the reaction mechanism of these redox enzymes by observing the electron transfer in real time. According to the number of publications on protein electrochemistry CYP has the third position after glucose oxidase and cytochrome c. CYP based enzyme electrodes for the quantification of drugs, metabolites or pesticides have been developed using different iso-enzymes. A crucial step in the sensor development is the efficiency of coupling the biocatalytic systems with the electrode is. In the 1970s the direct electron transfer of heme and heme peptides called microperoxidases (MPs) was used as model of oxidoreductases. They exhibit a broad substrate spectrum including hydroxylation of selected aromatic substrates, demethylation and epoxidation by means of hydrogen peroxide. It overlaps with that of P450 making heme and MPs to alternate recognition elements in biosensors for the detection of typical CYP substrates. In these enzyme electrodes the signal is generated by the conversion of all substrates thus representing in complex media an overall parameter. By combining the biocatalytic substrate conversion with selective binding to a molecularly imprinted polymer layer the specificity has been improved. Here we discuss different approaches of biosensors based on CYP, microperoxidases and catalytically active MIPs and discuss their potential as recognition elements in biosensors. The performance of these sensors and their further development are discussed. (C) 2013 Elsevier Ltd. All rights reserved.
KW  - Cytochrome P450
KW  - Microperoxidases
KW  - Catalytically active molecularly imprinted polymers
KW  - Biosensors
KW  - Personalised medicine
Y1  - 2013
U6  - https://doi.org/10.1016/j.electacta.2013.03.154
SN  - 0013-4686
SN  - 1873-3859
VL  - 110
SP  - 63
EP  - 72
PB  - PERGAMON-ELSEVIER SCIENCE LTD
CY  - OXFORD
ER  - 
TY  - JOUR
A1  - Yarman, Aysu
A1  - Schulz, Christopher
A1  - Sygmund, Cristoph
A1  - Ludwig, Roland
A1  - Gorton, Lo
A1  - Wollenberger, Ursula
A1  - Scheller, Frieder W.
T1  - Third generation ATP sensor with enzymatic analyte recycling
JF  - Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis
N2  - For the first time the direct electron transfer of an enzyme - cellobiose dehydrogenase, CDH - has been coupled with the hexokinase catalyzed competition for glucose in a sensor for ATP. To enhance the signal output for ATP, pyruvate kinase was coimmobilized to recycle ADP by the phosphoenolpyruvate driven reaction. The new sensor overcomes the limit of 1:1 stoichiometry of the sequential or competitive conversion of ATP by effective enzymatic recycling of the analyte. The anodic oxidation of the glucose converting CDH proceeds at electrode potentials below 0 mV vs. Ag vertical bar AgCl thus potentially interfering substances like ascorbic acid or catecholamines do not influence the measuring signal. The combination of direct electron transfer of CDH with the enzymatic recycling results in an interference-free and oxygen-independent measurement of ATP in the lower mu molar concentration range with a lower limit of detection of 63.3 nM (S/N=3).
KW  - ATP
KW  - Third generation sensor
KW  - Enzymatic recycling
KW  - Cellobiose dehydrogenase
KW  - Hexokinase
KW  - Pyruvate kinase
Y1  - 2014
U6  - https://doi.org/10.1002/elan.201400231
SN  - 1040-0397
SN  - 1521-4109
VL  - 26
IS  - 9
SP  - 2043
EP  - 2048
PB  - Wiley-VCH
CY  - Weinheim
ER  -